The present invention relates to cylinder apparatus such as a hydraulic shock absorber, a gas spring, etc. in which a rod extends from one end of a cylinder part.
In cylinder-type hydraulic shock absorbers attached to suspension systems of automobiles, for example, it is desirable to lock the piston rod near its minimum length position during transport and storage in view of the space efficiency and from the viewpoint of protecting the surface of the piston rod from rusting and being contaminated. However, in a hydraulic shock absorber having a gas sealed in the cylinder to pressurize the hydraulic fluid in the cylinder at all times in order to prevent cavitation or the like, the piston rod is, generally, extended by the gas pressure.
Conventionally, the piston rod is restrained in its minimum length position by using a synthetic resin band or a metallic wire. Alternatively, as disclosed, for example, in Japanese Utility Model Registration Application Publication No. Hei-2-132147, mutually engageable engaging members are attached to the hydraulic shock absorber body and the distal end of the piston rod, and these engaging members are engaged with each other to thereby lock the piston rod in its minimum length position.
However, the above-described conventional method using a synthetic resin band or a metallic wire involves the problem that it takes time and effort to cut the band or to untie the wire at the time of attaching the hydraulic shock absorber to a vehicle or the like. In addition, the conventional method needs time and effort to dispose of or recycle the used band or wire.
In the hydraulic shock absorber equipped with engaging members as disclosed in the above-mentioned Japanese Utility Model Registration Application Publication No. Hei-2-132147, the engaged condition of the engaging members cannot be visually confirmed for the reason, for example, that the piston rod is covered with a dust cover. It is conceivable to provide a window in the dust cover to allow visual inspection of the engaged condition. In such a case, however, visibility is not good because the engaged part is viewed through the window. Therefore, the provision of a window in the dust cover cannot be said to be a satisfactory solution.